<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>table</title>
  <style>
    table {
      border: 1px solid #ededed;
      /* 边框合并 */
      border-collapse: collapse;
    }

    tr td,
    tr th {
      border: 1px solid #ededed;

    }
  </style>
</head>

<body>
  <!-- student -->
  <table style="color: aqua;">
    <!-- 表头 -->
    <thead>
      <tr>
        <th>学号</th>
        <th>姓名</th>
        <th>性别</th>
        <th>年龄</th>
      </tr>
    </thead>
    <!-- 数据 -->
    <tbody>
      <tr>
        <td>1</td>
        <td>张三</td>
        <td>男</td>
        <td>20</td>
      </tr>
      <tr>
        <td>2</td>
        <td>张三2</td>
        <td>男</td>
        <td>20</td>
      </tr>
      <tr>
        <th>3</th>
        <th>张三3</th>
        <th>男</th>
        <th>20</th>
      </tr>
    </tbody>

  </table>
</body>

</html>